机载防撞系统干扰限制功能的设计与实现

针对机载防撞系统(TCAS)空对空通信时存在的同步混扰,采用飞机分布因子结合问询功率和问询速率的控制方法,建立了干扰限制的数学模型,给出了TCAS监视功能干扰限制的设计流程。按照DO-185B标准定义的高密度飞机分布环境,采用计算机仿真得到了TCAS干扰限制功能在高密度空域中统计性能,对不同监视区域中TCAS应答机的占用率与DO-185B的设计需求进行比较,验证了设计的干扰限制功能的有效性和实用性。仿真结果表明干扰限制算法能够满足高密度空域中TCAS监视功能的要求,在TCAS干扰限制功能的设计和性能评估方面具有实际应用价值。     

采用积分二次相位函数的雷达脉内调制类型识别

为了在低信噪比条件下获得较好的识别准确率,提出了一种基于积分二次相位函数（IQPF）的识别分类方法。根据不同信号的调频斜率的正负值完成信号的预分类,然后再利用不同信号的IQPF峰值-能量比以及功率谱估计实现信号的自动化分类。给出了识别流程图并进行了仿真实验,结果表明,该方法在信噪比大于-3dB时,其识别正确率达到90%以上,证明了方法的有效性和可行性。相关研究为雷达脉内调制类型的识别提供了一种切实可行的方法,具有一定的应用价值。     

Combining the Effects of OLS and Spread on Futures Hedging: Evidence from the Taiwan Stock Index

Abstract:

This study proposes a dynamic hedge ratio, the combined ordinary least squares spread (COLSS), which combines the hedge ratio of ordinary least squares and the value of spread. Using this dynamic ratio for hedging with futures contracts, one can replace spot risk with spread risk. The COLSS captures not only the long-run equilibrium between spot and futures returns, but also the short-run deviation from equilibrium. The spread is forecast by one-period lagged stock market factors and high-order moments that are estimated by an options model. In the in-sample and out-of-sample tests, the COLSS strategy achieves significant risk reduction and outperforms the alternative models by a large utility improvement.     

中国一线城市房租形成机理和调控对策

房租是由房屋租赁市场的需求和供给两个方面决定的,而房屋租赁市场的需求和供给都受到房屋交易市场所形成的房价的影响。房价对房屋租赁市场需求的影响主要是由于房屋租赁市场和房屋交易市场的替代效应所导致,房价对房屋租赁市场供给的影响主要由房屋租售比和房价的上涨幅度决定。我国一线城市房价近十年的平均年上涨率为10%左右,这导致了我国一线城市的房屋租售比维持在极低的水平。随着房价的平稳,房租必然大幅上涨,故必须采取措施增加一线城市房屋租赁市场的供给,以供给量的大幅增加稳定房租。     

Fiscal Stimulus in Times of High Debt: Reconsidering Multipliers and Twin Deficits

We investigate the impact of fiscal stimuli at different levels of the government debt‐to‐GDP ratio for a sample of 17 European countries from 1970 to 2010. This is implemented in an interacted panel VAR framework in which all coefficient parameters are allowed to change continuously with the debt‐to‐GDP ratio. We find that responses to government spending shocks exhibit strong nonlinear behavior. While the overall cumulative effect of a spending shock on real GDP is positive and significant at moderate debt‐to‐GDP ratios, this effect turns negative as the ratio increases. The total cumulative effect on the trade balance as a share of GDP is negative at first but switches sign at higher levels of debt. Consequently, depending on the degree of public indebtedness, our results accommodate long‐run fiscal multipliers that are greater and smaller than one or even negative as well as twin deficit and twin divergence behavior within one sample and time period. From a policy perspective, these results lend additional support to increased prudence at high public debt ratios because the effectiveness of fiscal stimuli to boost economic activity or resolve external imbalances may not be guaranteed.     

Monopoly versus Competition in Setting Accounting Standards

Financial accounting standards are set by organizations granted a significant degree of monopoly power by various governments. While there has been considerable debate on the merits of national (e.g., US Financial Accounting Standards Board (FASB)) versus international (International Accounting Standards Board (IASB)) monopolies, little attention has been paid to the merits of using competing standard‐setting organizations (SSOs) for setting accounting standards. We compare the standard‐setting processes of the FASB/IASB to the processes of four technology‐oriented SSOs to assess the role of competition. We also provide a case study of monopoly and competitive standards in telephony. Both telephony and accounting yield some gains from coordination, and similar arguments are used (under the labels of comparability and consistency of accounting) in debates about granting a monopoly to their respective SSOs. Our results show that a group of volunteers competing with the government‐sanctioned monopoly of International Telecommunications Union transformed the telephone industry. Thanks to this standards competition, we enjoy free video internet calling and massive cost savings. Implications for accounting standard setting are discussed.     

Investment Dynamics with Information Costs

Investment in physical capital at the microlevel is infrequent and large, or lumpy. The most common explanation for this is that firms face nonconvex physical adjustment costs. The model developed in this paper shows that information costs make investment lumpy at the microlevel, even in the absence of nonconvex adjustment costs. When collecting and processing information are costly, the firm optimally chooses to do it sporadically and to be inactive most of the time. This behavior results in infrequent and possibly large capital adjustments. The model fits plant‐level investment rate moments well, and it also matches some higher order moments of aggregate investment rates.     

Trade Openness and Exchange Rate Regimes

The paper evaluates the net welfare gains of inflation targeting over a fixed exchange rate as a function of a country's trade openness, using a multisectoral structural model calibrated to Chile. For most calibrations with separable preferences, net welfare gains are increasing in trade openness. The reason is that in more open economies terms of trade shocks, which favor inflation targeting, become quantitatively more important, while price markup shocks in the imperfectly competitive nontradables sector, which favor exchange rate targeting, become less important. The most important exception is heavily indebted countries, where net welfare gains are decreasing in trade openness.     

Labor‐Market Institutions and Long‐Term Effects of Youth Unemployment

Graduating from a school during a time of adverse economic conditions has a persistent, harmful effect on workers’ subsequent employment opportunities. An analysis of panel data from OECD countries during the 1960–2010 periods reveals that a worker who experiences a 1 percentage point higher unemployment rate while the worker is 16–24 years old has a 0.14 percentage point higher unemployment rate at ages 25–29 years and 0.03 percentage points higher at ages 30–34 years. The persistence of this negative effect is stronger in countries with stricter employment protection legislation. A composite index for labor‐market rigidity is constructed and the index is shown to have positive correlation with the persistence. Moderating macroeconomic fluctuations is more important in countries that have more persistent labor‐market entry effects on subsequent outcomes.     

Money and liquidity in financial markets

We argue that there is a connection between the interbank market for liquidity and the broader financial markets, which has its basis in demand for liquidity by banks. Tightness in the market for liquidity leads banks to engage in what we term “liquidity pull-back,” which involves selling financial assets either by banks directly or by levered investors. Empirical tests on the stock market are supportive. Tighter interbank markets are associated with relatively more volume in more liquid stocks; selling pressure, especially in more liquid stocks; and transitory negative returns. We control for market-wide uncertainty and in the process also contribute to the literature on portfolio rebalancing. Our general point is that money matters in financial markets.